We are a self-centered species, and what follows will seem like a particularly blatant example of it: Take polar bears, a species we are pushing rapidly toward extinction, and study them—quick, before it’s too late—to learn how their biological adaptations can help us cope with our own deep-fried, high-fat modern diet.

“For polar bears, profound obesity is a benign state,” said one researcher, in the press release for a new study being published today in the journal Cell. “We wanted to understand how they are able to cope with that,” said another. “If we learn a bit about the genes that allow them to deal with that, perhaps that will give us tools to modulate human physiology down the line.”

Wow, and could I please have a side of bacon with that?

OK, I think the press release was pandering (starting with the headline “Humans May Benefit…”). The scientists, possibly nudged along by the news office, were just succumbing to the myth that most people will care about the study of other species only to the extent that it might somehow make their own lives more comfortable. Let’s be honest, though, polar bears are amazing all by themselves, and that’s what this new research is really all about.

What interested the scientists was the chance to learn how polar bears have adapted to live all winter in some of the coldest and least hospitable conditions on Earth, without access to drinking water, subsisting almost entirely on a heart-attack diet of seal blubber and yet also swimming ultramarathon distances in the summer.

“How is that even possible?” said Eline Lorenzen in an interview. She’s a molecular ecologist at the University of California, Berkeley, and part of a team of researchers extending from Denmark to China who used detailed genetic analysis to understand not only the how but the why and the when of polar bear evolution.

Polar bears are a surprisingly new species. Other large mammals typically separate into new species, at most, once every million or 2 million years, said Lorenzen. Forest and savannah elephants, for instance, went their separate ways 3 million years ago. Humans and chimpanzees last shared a common ancestor perhaps 7 million years ago. But according to two separate genetic techniques used for the new study, polar bears evolved from brown bears just 479,000 to 343,000 years ago.

Moreover, they seem, based on analysis of an ancient polar bear jawbone, to have completed the shift to their present form and behavior 110,000 years ago. Assuming a generation time of just over 11 years, that represents a radical change in appearance, behavior, and physiology in as little as 20,500 generations. In evolutionary terms, that’s basically overnight.

How did they come to live like that? The timing of polar bear evolution coincided, according to the study, with a long period of unusually warm weather, which “could have enabled brown bears to colonize northern latitudes that were previously uninhabitable for the species.” But when the climate switched back to colder conditions, isolated populations either died or rapidly adapted to “some of the world’s harshest climates and most inhospitable conditions.”